Almost an hour into his first late-night patrol in Thawra, a Shiite Muslim enclave on Baghdad's east side, US Army Capt. Scott Masson hears a warning crackle across his radio: A man with an AK-47 assault rifle is moving through the shadows to the left of the captain's Humvee.
"Stop. Stop here," he says to the driver. He sprints across a darkened street, takes aim with his pistol, and shouts for the man to get down on the ground.
As soldiers recover the AK-47 under a nearby bus, the man reveals that rather than being a fedayeen fighter, he is merely attempting to settle a personal score.
Captain Masson lectures the now-disarmed and trembling man through an Arabic interpreter. "You are not allowed to carry weapons in public," he says. "And you need to go home ... now."
Although Masson and others in his unit came to Iraq prepared to wage all-out combat, they increasingly find themselves doing the work of police officers, attempting to keep the peace in a heavily armed, war-torn land.
Welcome to Part 2 of Operation Iraqi Freedom.
If the combat phase of the war was characterized by a quick, devastating, and decisive military assault on the Baathist government of Saddam Hussein, this second, more complicated stage is everything but quick, devastating, and decisive.
Instead, US forces are now facing the extremely difficult role of trying to fill a security vacuum left by one of the most ruthlessly efficient security apparatuses in the world. Exactly how they do it in the days and weeks ahead will go a long way in determining whether average Iraqi citizens cheer American soldiers as liberators or eventually fight and curse them as military occupiers.
Currently, the overall picture in Iraq remains mixed. Nearly three weeks after the fall of the Hussein regime, humanitarian assistance has yet to begin to flow in any substantial quantity to the Iraqi people. Thirty-seven of the 55 most wanted members of the Baath Party - including Mr. Hussein - remain at large. And looters and black-market profiteers are still operating, although not as widely as earlier.
On the positive side, police in Baghdad are reporting back to work, and water and electricity services are improving daily. Although there is still occasional gunfire, the city markets are full of fruit, vegetables, and fish, as well as shoppers.
Yet above it all is the issue of security and how best to foster an atmosphere that will allow the Iraqis to rebuild their own nation, US officials say.
Over the weekend, longer-term security plans continued to take shape, as France and Germany - two of America's harshest critics of the Iraq war - reluctantly endorsed a US plan to divide Iraq into three zones controlled by the US, Britain, and Poland. While France and Germany have been excluded from contributing troops to the zones, stabilization forces will include personnel from Bulgaria, Denmark, Italy, the Netherlands, Spain, and Ukraine.
Right now, though, American soldiers and officers like Masson are playing the key security role. It is their job to drive down Iraq's dusty streets and sometimes physically wrestle a gun out of Iraqi hands.
"These guys go out there every day and try to make a difference," says Col. Terry Wolff, commander of the 2nd Armored Cavalry Regiment out of Fort Polk, La., which is patrolling a large swath of eastern Baghdad. "When the people see us doing that, they are thankful."
Thankful can be an understatement. As Masson and his patrol of five Humvees move through the dark streets of Thawra, crowds gather along the road, sometimes erupting into a block-long cheering section. There is applause as well as waves and smiles. "Good Bush, America good," the children chant.
Such spontaneous expressions of gratitude seem incongruous in this dismal and forgotten corner of Iraq that had been sarcastically named by the prior regime Saddam City. In reality, this is a ghetto of 1.8 million residents that was barely permitted to exist at the fringe of Iraqi society.
The streets are littered with piles of burning trash. Even before the war, large sections had no electricity. Raw sewage flows where barefoot children play. This place has a reputation for being the poorest and most dangerous neighborhood in Baghdad. Even Hussein's own security agents dreaded coming here.
The experience has been somewhat different for Masson and his men.
"The American, I put him like a crown on my head," says Adel Abdul-Karim, a local barber. "I am so happy because America removed Saddam Hussein from power. I am 18 years old, and in my lifetime I have not seen anything like this."
Nor have the 18- and 20-year-old American soldiers in the Humvees. Many aren't sure what to make of it. But all of them are aware that their warm reception could turn very cold, very fast.
Even now, not everyone in Thawra supports the presence of US forces. Some children and even a few adults have thrown rocks at the Humvees. "I get hit five or six times a day," says Spc. John Spellmach, the gunner in Masson's Humvee.
Sometimes the rocks even come from within groups cheering the soldiers. "We get a whole crowd saying, 'Go USA, Go USA,' and then they start chucking stuff at us," says Specialist Spellmach. "It makes for a very frustrating day."
But he adds that rocks are preferable to bullets or rocket-propelled grenades.
Indeed, Saturday night, a gunman in a car sprayed a full clip of AK-47 ammunition out his window while passing in front of an Army Humvee. No one was hit, but US rules of engagement permit American soldiers to shoot back with deadly force if threatened or fired upon.
"I feel we had a right to open up on them," says Lt. Matt Cannon of St. Petersburg, Fla., who was sitting in the front right seat of the Humvee. The crew's gunner, Adrian Musquez of Beeville, Texas, who mans a roof-mounted heavy machine gun, said he saw the entire incident and could have easily leveled his weapon and pulled the trigger. "I could have killed them," he says.
But he didn't. The incident took place in a crowded intersection in the center of a market jammed with men, women, and children. He fired a warning shot into the air instead.
Then Lieutenant Cannon's Humvee and a second Humvee chased the car into a traffic jam and took the shooter and driver into custody. No shots were exchanged.
Cannon said the outcome might have been different if his truck had been struck by gunfire. "They were just really bad shots, and they were firing out of a moving car," he says.
"It is difficult trying to fight a war in the streets of a city. We try to be more careful so we only get the bad guys," continues Cannon. "If we fire back and civilian lives are lost, that could cause deterioration of our relationship with the community. All the work we've done to establish good relations with these people can be destroyed by an incident like that."
A similar situation developed in Fallujah, a town northwest of Baghdad, which was a Hussein stronghold before the war. The town remains tense after a series of clashes last week between US forces and local residents that left 18 Iraqis dead. The trouble started when American soldiers opened fire after they said someone shot at them during a street protest.